CaptureSync User Manual

For version 1.1
Written by Ben Bird

 

Table of Contents


Introduction

CaptureSync is an application for capturing multiple video and audio feeds to a single QuickTime movie file. All feeds are synchronised in the captured file, so that they will play back together in real time, exactly as they were captured.

CaptureSync has an easy and intuitive user interface: once your video and audio devices are set up, you start and stop the capture using a button in the main window. The captured files are saved to the location you specify in the General Preferences (by default, files are saved to the CaptureSync folder within your Documents folder).

CaptureSync supports a wide variety of video and audio inputs, including USB, FireWire and Thunderbolt devices, network devices, and screen captures. It can also capture the camera or screen of another Mac, via its companion product RemoteSight.

 

Setting Up Video Devices

CaptureSync support three distinct types of video inputs: local devices, network devices and screen captures - these are described below:

Local Video Devices

These are devices that connect to your Mac via USB, FireWire or Thunderbolt, or are built in to your Mac (iSight and FaceTime cameras).

Some local devices require driver software provided by the manufacturer to be installed (e.g. Blackmagic video input devices), while others work with driver software that is built in to Mac OS X (e.g. USB webcams that support the UVC protocol). Once the correct driver software is installed, local devices will be automatically detected by CaptureSync, so setup of these devices within the software is straightforward.

Except for DV devices connected by FireWire, local devices deliver uncompressed data, so CaptureSync will compress this data to JPEG or MPEG-4 format while recording (selectable via the General Preferences), for efficient captured file sizes. Simply open the Preferences window, click the Video tab, then click the plus button and you should see your device listed there. The available settings for local video devices are as follows:

Name - this is purely used within the software to refer to the device, so you can choose to specify a name here or leave it blank to use the default name.

Resolution and frame rate - these are the main determinants of the resulting quality of the video that will be captured from the device, so set these according to your needs, but note that as the resolution and frame rate increase, so does the CPU load on your Mac as well as the file size of the captured movie files.

Input - this allows you to choose between the device's inputs, if it has more than one.

Notes for local video devices:

Network Video Devices

These are devices that connect to your Mac via a wired (ethernet) or wireless (WiFi) network, so they aren't restricted by the relatively short cable lengths required for local devices. CaptureSync supports most network cameras and network video servers on the market. There's a wide variety of cameras available, from cheap low-resolution webcam-type cameras to very high-quality multi-megapixel models. Whatever your requirements, you will be able to find one that meets them.

Network devices have one further major advantage over local devices, in that they supply compressed video data. This means that CaptureSync can record this data directly to the captured movie file with no further compression, which saves CPU resources. It also means that it is possible to use a large number of cameras simultaneously over one network, due to the efficient bandwidth of the compressed video streams.

Before you first use a new network device, it will need to be configured for your network, so please follow our online guide Setting Up Network Devices before adding the device to CaptureSync.

To add a network device, click the plus button and select "Add network device". The available settings for network devices are as follows:

Name - this is purely used within the software to refer to the device, so you can choose to specify a name here or leave it blank to use the default name.

Address - this is the IP address or hostname of the device.

Username and password - enter the device's username (normally "admin") and corresponding password.

HTTP and RTSP port - if the device uses non-standard ports, enter them here (most devices use standard HTTP and RTSP ports, which are 80 and 554 respectively).

Device type - from the list, select a profile that most closely matches the make and model of your device.

Format - choose the format of video you want the device to sent to CaptureSync. There are three main choices: JPEG, MPEG-4 or H.264. JPEG uses the lowest amount of CPU resources to process, however it uses the highest amount of network bandwidth and produces the largest captured files. Both MPEG-4 and H.264 use more CPU resources, but are much more bandwidth-efficient and produce much smaller captured files (H.264 is around twice as bandwidth-efficient as MPEG-4, which is around five times more bandwidth-efficient as JPEG). If your device supports H.264 then this is generally the best format to use. Depending on your device you may have an choice between RTSP and RTSP-over-HTTP for the transport protocol. If you are connecting to the device over a local network then it doesn't matter what you choose, but if you are connecting over the internet, then RTSP-over-HTTP is preferable.

Input - many devices have multiple inputs, which may correspond to actual physical inputs on the device, or differently-configured video profiles.

Resolution and frame rate - these are the main determinants of the resulting quality of the video that will be captured from the device, so set these according to your needs, but note that as the resolution and frame rate increase, so does the CPU load on your Mac as well as the file size of the captured movie files. If these options are unavailable then you should connect to the device directly using a web browser in order to configure these parameters.

Request - one of the profiles in the device type list is "Manual", which allows you to manually set up a device by specifying the request that the device understand for video streaming. This information may be obtained from the device's manufacturer or may be specified in its user manual. For example, if the manual states that the video streaming URL is rtsp://address/video.sdp, then you would select RTSP as the Format and enter video.sdp as the Request.

Notes for network video devices:

Screen Captures

CaptureSync has the ability to capture the screen image from any monitor attached to your Mac. You can add a screen capture "device" via the plus button just like any other video device. The available settings for screen capture devices are as follows:

Name - this is purely used within the software to refer to the device, so you can choose to specify a name here or leave it blank to use the default name.

Resolution and frame rate - these are the main determinants of the resulting quality of the video that will be captured from the screen, so set these according to your needs, but note that as the resolution and frame rate increase, so does the CPU load on your Mac as well as the file size of the captured movie files.

Mouse cursor - you can choose to omit the mouse cursor, or include one of varying sizes.

Notes for screen captures:

 

Setting Up Audio Devices

CaptureSync supports two distinct types of audio inputs: local devices and network devices - these are described below:

Local Audio Devices

These are USB, FireWire or Thunderbolt devices, or built-in audio inputs of your Mac. Any device that advertises Mac compatibility will work with CaptureSync. Under the Audio tab of the Preferences window, click the plus button to add a device. The available settings for local audio devices are as follows:

Name - this is purely used within the software to refer to the device, so you can choose to specify a name here or leave it blank to use the default name.

Quality - choose between low, medium and high. CaptureSync will automatically select appropriate recording parameters. Typical parameters are as follows:

Channels - each audio track created in the captured movie file can have either one or two channels. If there is only one channel, then this is treated as mono audio, and will play back in both the left and right speakers. However if there are two channels recorded to the track, then this will be played back as stereo sound, with each channel assigned to its own speaker. These channel controls allow you to assign physical inputs on the device to these two audio track channels. Most devices only have one or two inputs (designed for mono or stereo audio), but some more sophisticated devices have more than two inputs.

Notes for local audio devices:

Network Audio Devices

These are audio streams that are delivered over a network from a network video device (e.g. an IP camera). If you have set up a network video device that supports audio, then you will have an option, via the plus button , to add its corresponding audio input. The available settings for network audio devices are as follows:

The name setting is purely used within the software to refer to the device, so you can choose to specify a name here or leave it blank to use the default name.

The quality and channel settings are not available for network devices, because these must be set directly in the device itself. Connect to the device directly using a web browser in order to view and adjust its settings.

Notes for network audio devices:

 

General Preferences

Capture destination - this is the folder where CaptureSync creates captured movie files; click on this control to change the location.

Capture size - this specifies the resulting size of the captured movie files. You can choose to capture at the same size as CaptureSync's video window, or at a custom size of your choosing.

Video compression - this is the compression that is applied to video from local video devices and screen captures (video from network devices is already compressed and will be captured as-is). There are two choices: JPEG and MPEG-4; JPEG is faster to compress, and so will use less of your Mac's CPU resources, however it will produce larger captured file sizes. Conversely, MPEG-4 uses more CPU resources but produces much smaller file sizes. MPEG-4 is normally the best option.

Time stamp options - you can choose to include a time stamp in captured movie files, which comprises the date and time in the top left corner of the movie. Choose between a 24-hour clock ("08:30:00", "16:30:00" etc.) or a 12-hour clock ("8:30:00 AM", "4:30:00 PM" etc.)

Date ordering - choose what order you would like the day, month and year arranged in the time stamps and file names of captured movie files.

 

Optimising Performance

Capturing video and audio from multiple devices can require significant CPU resources. Here are some tips to help you get the most out of CaptureSync:

 

Splitting Multi-Track Movie Files

The multi-track movie files produced by CaptureSync can be played back using Apple's QuickTime Player software, however if you need to import the captured movie into editing software such as Final Cut Pro, you will first need to split it into individual tracks. To do this, use the Split Multi-Track Movie File option in the File menu in CaptureSync: select a file to process, and CaptureSync will generate a folder containing individual movie files for each track in the source file. These individual movie files can then be imported into Final Cut Pro for editing. The actual video and audio data itself is not modified - just the file structure - so there is no loss of quality associated with this procedure.

 

Troubleshooting

Error messages

Whenever an error occurs, CaptureSync will write a description of the error to the Console log, so if you are having any problems, please check this log as it should provide useful information about what is going wrong. You will find the Console in your Utilities folder within your Applications folder.

If an error occurs that results in a video or audio device being closed, CaptureSync will continuously attempt to reconnect to the device until it is back online. If a recording is currently taking place, this will result in a black or silent segment for the video or audio device in question.

USB bandwidth

If you are using USB devices and you get a message about lack of bandwidth, this means that the devices are consuming more bandwidth than is available on the USB bus. In this case, try connecting the devices to different ports on your Mac (some ports will share bandwidth, others will be independent), or reduce the frame rate and resolution of the devices.

Network communication problems

If you are using network devices and you are getting intermittent connection errors, then your network could be at fault. If you are using wireless cameras, make sure that the cameras are well within range of the access point and that you aren't overloading the wireless network with too many devices. If possible, connect your devices using wired ethernet instead, as this will provide much better performance and reliability.

If your network devices are connected by wired ethernet, make sure that you are using a high-quality ethernet switch as the centre of your network (Netgear have a good range of high-quality switches). Don't rely on the ethernet ports built into routers - these will often cause problems if used in a demanding environment.

Stuttering captures

If you are having problems with slow or stuttering captures, or loss of synchronisation between different feeds, this could indicate that your Mac is having trouble keeping up with processing the incoming data. Please see the Optimising Performance section for advice on how to reduce CPU resource usage.

Audio/Video drift

When the clock generating the audio samples (which may be in a network camera or other external device) is different from the clock generating time stamps for the video samples (which is always your Mac's internal clock), then this results in desynchronisation (drift) of the video and audio streams over a sufficiently long period of time. Clocks of the type used in computers and cameras (which are quartz crystal oscillators) have finite precision, and two different clocks will inevitably go out of sync with each other, sometimes by several seconds per hour. CaptureSync will detect and correct for this phenomenon when the drift exceeds one second, so if you notice a slight drift over time, you should see that this will automatically correct itself.

You will not encounter this problem if you are using your Mac's built-in audio inputs, or if your captures are sufficiently short.

Differing start times of video tracks

In your captured movie files, you may observe that the video stream for some cameras starts a few seconds after others, leaving a short blank gap at the start of the movie. This occurs due to the nature of the video format being received from network video devices. The MPEG-4 and H.264 formats are temporally compressed, with one key frame (I-frame) followed by several delta frames (P-frames), where the delta frames contain only changes in the image since the last frame. This is what makes these formats so bandwidth-efficient, but it also means that any sequence must start on a key frame. The gap occurs because CaptureSync has to wait for a key frame in order to start recording the video stream to the captured movie file. You can minimise this gap by lowering the key frame rate (also called I-frame interval or GOV length) in the device's settings, but note that a lower key frame rate will produce a higher-bandwidth stream. One key frame every few seconds generally works well, so if the camera is streaming at 5fps, then this corresponds to one key frame every 15 or so frames.

 

Help

If you need help using the software, or have any questions, please first have a look through the CaptureSync online help pages to see if your question is answered there. If not, feel free to email us and we will do our best to help.

 

Appendix 1:
Supported Local Video Devices

CaptureSync supports the following local video devices:

 

Appendix 2:
Supported Network Video Devices

Please see our web site for the full list of supported IP cameras, which is frequently updated with new models. Any camera on this list will work with CaptureSync, and additionally any device that advertises ONVIF compliance should also work.

Supported network video servers are listed below. A Network video server is an analog-to-digital video input device that accepts a standard analog video signal and delivers a compressed digital video stream over a network. Note that while network cameras can produce very high-quality video and many have multi-megapixel sensors, network video servers are designed as input devices for older-style analog cameras, and the resolution of these is limited. The following video servers are supported by CaptureSync: